U.S. patent number 5,254,425 [Application Number 07/615,948] was granted by the patent office on 1993-10-19 for self-dispersing colorant, liquid developing agent for electrostatic photography, toner supply and toner kit.
This patent grant is currently assigned to Fuji Photo Film Co., Ltd.. Invention is credited to Yutaka Sakasai, Nobuo Suzuki, Hiromichi Tachikawa.
United States Patent |
5,254,425 |
Suzuki , et al. |
October 19, 1993 |
Self-dispersing colorant, liquid developing agent for electrostatic
photography, toner supply and toner kit
Abstract
A self-dispersing graft-copolymer capable of self-dispersion in
a high-electrical insulating carrier liquid to form grains therein.
The graft-copolymer is combined with a pigment or dye to provide a
self-dispersing solid colorant, which is suitable as a toner or
toner supply for a liquid developing agent for electrostatic
photography. The colorant is also applicable to a printing ink, an
ink for an ink-jet system or a coating paint composition. The
colorant well self-disperses in a carrier liquid to form well
dispersed grains therein without the necessity of mechanical
dispersing means.
Inventors: |
Suzuki; Nobuo (Kanagawa,
JP), Sakasai; Yutaka (Kanagawa, JP),
Tachikawa; Hiromichi (Kanagawa, JP) |
Assignee: |
Fuji Photo Film Co., Ltd.
(Kanagawa, JP)
|
Family
ID: |
17892617 |
Appl.
No.: |
07/615,948 |
Filed: |
November 20, 1990 |
Foreign Application Priority Data
|
|
|
|
|
Nov 20, 1989 [JP] |
|
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1-301079 |
|
Current U.S.
Class: |
430/115;
430/137.15 |
Current CPC
Class: |
G03G
9/133 (20130101); C09D 17/00 (20130101) |
Current International
Class: |
C09D
17/00 (20060101); G03G 9/12 (20060101); G03G
9/13 (20060101); G03G 009/13 () |
Field of
Search: |
;430/114,115,137 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Goodrow; John
Attorney, Agent or Firm: Sughrue, Mion, Zinn, Macpeak &
Seas
Claims
What is claimed is:
1. A liquid developing agent for electrostatic photography, which
comprises toner grains at least containing a resin, dispersed in a
high-electrical insulating carrier liquid, wherein the resin is a
self-dispersing graft-copolymer capable of self-dispersing in the
carrier liquid to form said toner grains,
wherein the self-dispersing graft-copolymer is formed from a
macromonomer having a polymerizable functional group at its
terminal and a comonomer, wherein said macromonomer is formed from
one of (a) a monomer forming moiety which is insoluble in the
carrier liquid or (b) a monomer forming moiety which is soluble in
the carrier liquid, and said comonomer is formed from the other of
the monomer forming moiety (a) or (b),
the insoluble monomer forming moiety is represented by formula (1):
##STR17## wherein R.sub.1 represents a hydrogen atom or a methyl
group;
R.sub.2 represents --COOR.sub.3, --O--COR.sub.3, ##STR18## or --CN;
R.sub.3 represents a substituted or unsubstituted alkyl group
having from 1 to 3 carbon atoms, a cycloalkyl group having from 3
to 8 carbon atoms, or a residue or a crosslinked hydrocarbon
compound having 4 to 18 carbon atoms;
R.sub.4 represents a hydrogen atom, an alkyl group having from 1 to
4 carbon atoms, a halogen atom, a nitro group, a cyano group or a
phenyl group, with the number of R.sub.4 's being from 1 to 3;
R.sub.5 represents a hydrogen atom, a methyl group, an ethyl group,
a halogen atom, a nitro group, a cyano group or a hydroxyl group,
with the number of R.sub.5 's being from 1 to 3; and
R.sub.6 and R.sub.7, which may be the same or different, each
represents an alkyl group having from 1 to 4; and
the soluble monomer forming moiety is represented by formula (2):
##STR19## wherein R.sub.1 represents a hydrogen atom or a methyl
group;
R.sub.8 represent --COOR.sub.9, --O--COR.sub.9, --OR.sub.9,
##STR20## R.sub.9 represents a linear or branched, substituted or
unsubstituted, alkyl group having from 6 to 22 carbon atoms;
R.sub.10 represents a linear or branched, substituted or
unsubstituted, alkyl group having from 4 to 12 carbon atoms;
and
l represents from 0 to 6; and m represents 0 or 1.
2. A solid toner for supply to a liquid developing agent for
electrostatic photography, which comprises toner grains at least
containing a resin dispersed in a high-electrical insulating
carrier liquid, where the toner comprises a self-dispersing
graft-copolymer capable of self-dispersion in a high-electrical
insulating carrier liquid to form said toner grains, or a
self-dispersing solid colorant containing at least one of a
pigment, a dye, a charge-adjusting agent and a dispersion
stabilizer in the graft-copolymer.
3. The solid toner for supply to a liquid developing agent for
electrostatic photography as in claim 2, in which the
self-dispersing graft-copolymer comprises monomer forming moieties
which are insoluble in the carrier liquid and monomer forming
moieties which are soluble in the carrier liquid.
4. The solid toner for supply to a liquid developing agent for
electrostatic photography as in claim 3, in which the
self-dispersing graft-copolymer is formed from a macromonomer
having a polymerizable functional group at its terminal.
5. The solid toner for supply to a liquid developing agent for
electrostatic photography as in claim 3, in which the insoluble
monomers are those of the general formula (1): ##STR21## wherein
R.sub.1 represents a hydrogen atom or a methyl group;
R.sub.2 represents --COOR.sub.3, --O--COR.sub.3, ##STR22## or CN;
R.sub.3 represents a substituted or unsubstituted alkyl group
having from 1 to 3 carbon atoms, a cycloalkyl group having from 3
to 8 carbon atoms, or a residue of a crosslinked hydrocarbon
compound having 4 to 18 carbon atoms;
R.sub.4 represents a hydrogen atom, an alkyl group having from 1 to
4 carbon atoms, a halogen atom, a nitro group, a cyano group or a
phenyl group, with the number of R.sub.4 's being from 1 to 3;
n is 0 to 2 and m is 0 or 1;
R.sub.5 represents a hydrogen atom, a methyl group, an ethyl group,
a halogen atom, a nitro group, a cyano group or a hydroxyl group,
the number of R.sub.5 's being from 1 to 3; and
R.sub.6 and R.sub.7, which may be the same or different, each
represents an alkyl group having from 1 to 4.
6. A toner kit for a liquid developing agent for electrostatic
photography, comprising a self-dispersing solid graft-copolymer
capable of self-dispersion in a high-electrical insulating carrier
liquid to form grains therein or a self-dispersing solid colorant
containing at least one of a pigment, a dye, a charge-adjusting
agent and a dispersion stabilizer in the graft-copolymer, and a
high-electrical insulating carrier liquid or a high-electrical
insulating carrier liquid composition containing at least one of a
charge-adjusting agent and a dispersion stabilizer.
7. The solid toner for supply to a liquid developing agent for
electrostatic photography as in claim 6, in which the soluble
monomers are those of the general formula (2): ##STR23## wherein
R.sub.1 represents a hydrogen atom or a methyl group; R.sub.8
represents --COOR.sub.9, --O--COR.sub.9, --OR.sub.9, ##STR24##
R.sub.9 represents a linear or branched substituted or
unsubstituted alkyl group having from 6 to 22 carbon atoms;
R.sub.10 represents a linear or branched substituted or
unsubstituted alkyl group having from 4 to 12 carbon atoms; and
l represents from 0 to 6; and m represents 0 or 1.
8. The toner kit for a liquid developing agent for electrostatic
photography s in claim 6, in which the self dispersing
graft-copolymer is formed from a macromonomer having a
polyfunctional group at its terminal.
9. The toner kit for a liquid developing agent for electrostatic
photography as in claim 6, in which the self dispersing
graft-copolymer comprises monomer forming moieties which are
insoluble in the carrier liquid and monomer forming moieties which
are soluble in the carrier liquid.
10. The toner kit for a liquid developing agent for electrostatic
photography as in claim 9, in which the insoluble monomers are
those of the general formula (1): ##STR25## wherein R.sub.1
represents a hydrogen atom or a methyl group;
R.sub.2 represents --COOR.sub.3, --O--COR.sub.3, ##STR26## or CN;
R.sub.3 represents a substituted or unsubstituted alkyl group
having from 1 to 3 carbon atoms, a cycloalkyl group having from 3
to 8 carbon atoms, or a residue of a crosslinked hydrocarbon
compound having 4 to 18 carbon atoms;
R.sub.4 represents a hydrogen atom, an alkyl group having from 1 to
4 carbon atoms, a halogen atom, a nitro group, a cyano group or a
phenyl group, with the number of R.sub.4 's being from 1 to 3;
n is from 0 to 2 and m is 0 or 1;
R.sub.5 represents a hydrogen atom, a methyl group, an ethyl group,
a halogen atom, a nitro group, a cyano group or a hydroxyl group,
with the number of R.sub.5 's being from 1 to 3; and
R.sub.6 and R.sub.7, which may be the same or different, each
represents an alkyl group having from 1 to 4.
11. The toner kit for a liquid developing agent for electrostatic
photography as in claim 9, in which the soluble monomers are those
of the general formula (2): ##STR27## wherein R.sub.1 represents a
hydrogen atom or a methyl group;
R.sub.8 represents --COOR.sub.9, --O--COR.sub.9, --OR.sub.9,
##STR28## R.sub.9 represents a linear or branched substituted or
unsubstituted alkyl group having from 6 to 22 carbon atoms;
R.sub.10 represents a linear or branched substituted or
unsubstituted alkyl group having from 4 to 12 carbon atoms; and
l represents from 0 to 6; and m represents 0 or 1.
12. The liquid developing agent for electrostatic photography as in
claim 1, wherein the amount of macromonomer is 50 wt % or more of
the graft-copolymer.
Description
FIELD OF THE INVENTION
The present invention relates to a colorant which is composed of a
resin and a pigment or dye and which is used in preparing a liquid
developing agent for electrostatic photography, a printing ink, an
ink for an ink-jet system and a coating paint composition, as well
as to use of the colorant as a component in a liquid developing
agent, a toner supply and a toner kit for electrostatic
photography.
BACKGROUND OF THE INVENTION
As a colorant and a toner to be in a liquid developing agent for
electrostatic photography, a printing ink, an ink for an ink-jet
system and a coating paint composition, a pigment or dye or a
colorant prepared by coating a pigment or dye with a fixing resin
should be dispersed in a carrier liquid in a stable manner.
Additionally, a printed product, a coated product or an image
obtained by the use of the developing agent, ink or coating paint
composition should also have a high coloration degree and a high
image density and should additionally provide a sharp image. In
particular, in a liquid developing agent for electrostatic
photography, since the image-forming forming grains of a so-called
toner, which are dispersed in a highly-insulating non-aqueous
solvent, greatly influence the quality of the image developed with
the agent, toner grains in particular should have good
dispersibility.
Two methods--a dry developing method and a liquid developing
method--in general are approaches used forming a visual image from
an electrostatic latent image as formed in an electrostatic
photographic process. The liquid developing method is superior to
the dry developing method, since minute toner grains can be used
and fine images or halftone images can be faithfully
reproduced.
In general, a liquid developing agent for electrostatic photography
comprises a colorant such as various pigments or dyes, with carbon
black being a typical example, a coating agent which adsorbs onto
or coats the colorant for adjusting the charge of the colorant or
for imparting a fixing property to the colorant, a dispersing agent
for dispersing the toner grains, a charge-adjusting agent to adjust
the polarity and the amount of charge of the toner grains, and a
highly electrically-insulating non-aqueous solvent carrier liquid
having a dielectric constant of 3 or less and a volume resistivity
of 10.sup.9 .OMEGA.cm or more. The agent does not need to contain a
pigment or dye, when it is applied to a printing plate where the
toner image should have only an ink-adhering property, when it is
used in preparing a printing plate using an etching liquid, the
agent also does not need to contain a pigment or dye and only needs
to have resist properties. A liquid developing agent, a printing
ink and a coating paint composition are generally prepared using
the following method. More specifically, a pigment or dye and a
fixing resin, or a pigment or dye coated with a fixing resin is
converted directly into a powder of the desired size or in a dry
system. Thereafter it is dispersed in a dispersing agent-containing
a high-electrical resistance non-aqueous solvent using a
wet-dispersing machine such as a ball mill, a paint shaker or a
sand mill, to obtain a thick dispersion. The thus prepared thick
dispersion is used directly or after dilution with a solvent. In
preparing a liquid developing agent, the thick dispersion is added
to a charge-adjusting agent-containing carrier liquid to obtain a
liquid developing agent having a positive or negative polarity.
Alternatively, a different method can be used in which monomers
capable of forming a polymer which is insoluble in a carrier liquid
are polymerized in the carrier liquid in the presence of a polymer
which is soluble in the carrier liquid to form resin grains
(dispersion polymerization), and the grains are dyed with a dye, or
they are added to a charge-adjusting agent-containing carrier
liquid along with a separately dispersed pigment to prepare a
liquid developing agent, an ink or a coating paint composition.
Accordingly, a mechanical dispersing means or a granulating means
for dispersion polymerization or the like is necessary in order to
prepare toner grains of a liquid developing agent, or an ink or a
coating paint composition. Additionally, this is conducted in a
carrier liquid, and the formed dispersion is stored before use in
the carrier liquid or diluted with a dispersing liquid or carrier
liquid. Accordingly, the dispersion being stored is influenced by
the ambient temperature and humidity during transportation or
storage before use. This results in a variation in the
characteristics of the dispersion, such as grain size or viscosity
thereof, as compared with the characteristics of the corresponding
fresh dispersion immediately after preparation. As discussed above,
in the case of a liquid developing agent, a charge-adjusting agent
is added to the toner grains present in the liquid developing agent
in order that the positive or negative polarity of the grains and
the charged amount thereof are held constant. Additionally, the
toner further contains a fixing resin for the purpose of providing
fixing properties thereto, in addition to a pigment or dye.
Therefore, the charge-adjusting agent and the fixing resin often
separate from the pigment or dye (de-coating) as a result of
variations in the ambient temperature and humidity conditions
during transportation or storage or with the lapse of time on
storage. This results in variations in the charged amount or a
coagulation of the toner grains. As a result, the characteristics
of the stored liquid developing agent vary which adversely
influences the quality of the images formed with the agent.
In order to overcome the problems, for example, search for a more
stable charge-adjusting agent, development of a better combination
of pigment and coating agent resin, and search for a coating agent
resin which scarcely undergoes de-coating are being conducted. In
addition, investigation of better dispersing means and search for a
better dispersing agent are also being conducted to overcome the
time-dependent variation in the dispersing properties of the
developing agent. However, since the above-mentioned phenomena are
intrinsic problems in a liquid dispersion system it is difficult to
completely solve these problems.
The best method of solving the problems is to prepare a liquid
developing agent (toner) just before its use and the fresh agent is
not stored but is used immediately. One example of a method is to
add a toner for supply to a developing agent being used in
depending on the amount of the toner used. However, since the toner
supplied in this method is a high-density dispersion, the toner of
itself varies with the lapse of time during storage thereof.
Accordingly, this method can not be used to solve these
problems.
JP-A-1-113766 (the term "JP-A" as used herein means an "unexamined
published Japanese patent application") discloses a toner for
supply which is in the form of a solid tablet. This is prepared by
tableting toner grains with a binder resin which is soluble in a
carrier liquid. In the illustrated method, a colorant or a flashed
colorant and a resin are first dispersed in a liquid carrier with a
dispersing agent to obtain a thick dispersion, and this is filtered
by forced filtration, then dried and powdered with a mixer to
obtain a powder. Next, the resulting powder is tableted with a
binder which is soluble in the carrier liquid. Suitable binders
which can be used are paraffin wax, higher fatty acids, higher
alcohols and higher fatty acid esters. However, the method is
extremely complicated, and the forced filtration of the thick
dispersion is, in particular, not practical. Additionally, drying
of the filtered dispersion residue induces re-coagulation of the
toner grains, whereby a redispersion of the tableted toner is
difficult.
JP-A-63-194270 illustrates a method where a high polymer substance
having a melting point in the vicinity of room temperature is added
to a commercial liquid developing agent to gel and solidify the
liquid developing agent, and the solidified agent is heated to
liquify it just before use. In this method, the agent may be either
a solid or a liquid by repeatedly cooling and heating the same. The
solid state as referred to therein means a gel state which contains
a liquid component. Therefore, the developing agent gel becomes
liquid when the ambient temperature rises. In practical use of this
agent, this agent is often inconvenient to use since it becomes
liquid as the ambient temperature rises even though it should be
solid.
In view of the above, a solid self-dispersing colorant which is
capable of dispersion by itself to form a stable dispersion only
when it is added to a carrier liquid, as well as a liquid
developing agent for electrostatic photography which contains such
a colorant, and a toner for supply to a liquid developing agent and
a toner kit also containing such a colorant have not been developed
at present.
SUMMARY OF THE INVENTION
Thus, the present invention is developed toward a self-dispersing
colorant which may be used to produce a stable dispersion only when
it is added to a carrier liquid as well as a self-dispersing
graft-copolymer to be used in preparing such a colorant.
Accordingly, a first object of the present invention is to provide
a self-dispersing solid colorant capable of self-dispersion to
provide a stable dispersion only when it is added to a carrier
liquid.
A second object of the present invention is to provide a liquid
developing agent for electrostatic photography, which is prepared
from a self-dispersible resin substance and a colorant.
A third object of the present invention is to provide a solid toner
for supply to a liquid developing agent for electrostatic
photography.
A fourth object of the present invention is to provide a toner kit
which is composed of a complete solid toner and a carrier
liquid.
A fifth object of the present invention is to provide a liquid
developing agent for electrostatic photography, which is free from
the problems of time-dependent in stability.
The present inventors have found that a self-dispersing
graft-copolymer is obtained from a component insoluble in a carrier
liquid and a component soluble in a carrier liquid and is
preferably usable as a resin of a colorant or toner. In particular,
the graft-copolymer preferably contains a monomer component where a
graft moiety thereto is a macromonomer. Using the graft-copolymer,
a self-dispersing colorant, a stably dispersed liquid developing
agent, a toner supply and a toner kit have been obtain.
Specifically, the above-mentioned objects of the present invention
are attained by a self-dispersing solid colorant comprising a
self-dispersing graft-copolymer capable of self-dispersion in a
high-electrically insulating carrier liquid to form grains and a
pigment or dye.
One preferred embodiment of the present invention provides a
self-dispersing graft-copolymer such that the monomer forming the
graft moiety is a macromonomer having a polymerizable functional
group at its terminal.
Another embodiment of the present invention provides a liquid
developing agent for electrophotography which contains toner grains
at least containing a resin, as dispersed in a high-electrically
insulating carrier liquid and wherein the resin is a
self-dispersing graft-copolymer capable of self-dispersion in the
carrier liquid to form grains.
Still another embodiment of the present invention provides a
self-dispersing graft-copolymer in the developing agent such that
the monomer forming the graft moiety is a macromonomer having a
polymerizable functional group at its terminal.
Still another embodiment of the present invention provides a solid
toner for supply to a liquid developing agent for electrostatic
photography, which contains toner grains at least containing a
resin and dispersed in a high-insulating carrier liquid, where the
toner supply is a self-dispersing graft-copolymer capable of
self-dispersion in a high-insulating carrier liquid to form grains,
or a self-dispersing solid colorant containing at least one of a
pigment, a dye, a charge-adjusting agent and a dispersion
stabilizer in the graft-copolymer.
Still another embodiment of the present invention is such that the
graft-copolymer in the solid toner supply is produced from a
monomer forming the graft moiety which is a macromonomer having a
polymerizable functional group at its terminal.
Still another embodiment of the present invention provides a toner
kit for a liquid developing agent for electrostatic photography,
which is composed of a self-dispersing graft-copolymer capable of
self-dispersion in a high-insulating carrier liquid to form grains
or a self-dispersing solid colorant containing at least one of a
pigment, a dye, a charge-adjusting agent and a dispersion
stabilizer in the graft-copolymer, and a high-insulating carrier
liquid or a high-insulating carrier liquid composition containing
at least one of a charge-adjusting agent and a dispersion
stabilizer.
In still another embodiment of the present invention, the
graft-copolymer in the toner kit is such that the monomer forming
the graft moiety is a macromonomer having a polymerizable
functional group at the terminal of the monomer.
DETAILED DESCRIPTION OF THE INVENTION
The term "self-dispersibility" as used herein means that the
colorant or resin in a solid form (for example, in the form of
mass, tablet, granule or powder) spontaneously disperses in a
carrier liquid without any means such as mechanical dispersion to
form grains in the liquid. The "solid" form means that the
substance is solid at room temperature and in any desired form such
as a mass, tablet, granule or powder.
The term "toner supply" means a liquid developing agent for
replenishment that is added to a liquid developing agent during or
after use thereof so that the latter agent may again be used for
further forming images. Specifically, the term "toner supply" as
referred to herein means a solid dispersant precursor consisting
essentially of an image-forming toner grain component. The term
"toner kit" as used herein means a combination of a solid
essentially forming toner grains and a liquid consisting
essentially of a liquid carrier, where the blending of the two
produces a liquid developing agent.
The term "macromonomer" as used herein means a polymer having a
polymerizable functional group at the terminal of the molecule, as
is described in New Encyclopedia of High Polymers (edited by Japan
High Polymer Society, 1st Ed., issued in 1988, published by Asakura
Publishing Co.). Examples of suitable functional groups are a
double bond-containing vinyl group, a polymerizable double bond
group, or an ethylenically unsaturated group or other
polycondensable functional groups such as a carboxyl group, a
hydroxyl group, an amino group, an epoxy group, an isocyanate group
and an acid anhydride containing group.
Graft-copolymers of the present invention, which are produced by
the use of such a macromonomer, have characteristics such that the
structure is distinct and the amount of impurities therein is
small, as so clarified in the above-mentioned New Encyclopedia of
High Polymers.
The present invention is explained in greater detail hereunder.
A colorant which comprises a coloring agent and a fixing resin and
which is in a liquid developing agent for electrostatic
photography, a printing ink, an ink for ink-jet system or a coating
paint composition should be finely dispersed in a carrier liquid
and stably dispersed therein without coagulation or flocculation.
For this purpose, a colorant composed of a coloring agent and a
fixing resin can be dispersed using a mechanical dispersing means,
for example, a ball mill, a three-roll mill, an attritor, a
dynomill, a sand grinder or the like, to form fine grains using
prior art technique. As opposed to this, the present invention
provides a novel dispersion system which does not require a
mechanical dispersing means or a granulating means by dispersion
polymerization. Specifically, in accordance with the present
invention, the colorant only needs to be added to a carrier liquid
to form a stable dispersion system.
Examples of fixing resins present in conventional liquid developing
agents for electrostatic photography are for example, various known
resins which are insoluble or swellable in a carrier liquid.
For instance, examples include rubbers such as butadiene rubbers,
styrene-butadiene rubbers, cyclized rubbers or natural rubbers;
synthetic resins such as styrene resins, vinyltoluene resins,
acrylic resins, methacrylic resins, polyester resins, polycarbonate
resins or polyvinyl acetate resins; rosin resins; hydrogenated
rosin resins; alkyd resins including modified alkyl resins such as
linseed oil-modified alkyl resins; and natural resins such as
polyterpenes. Additional examples are phenol resins including
modified phenol resins such as phenol-formaldehyde resins, as well
as natural resin-modified maleic acid resins, pentaerythritol
phthalates, chroman-indene resins, ester gum resins, and vegetable
oil polyamides.
These resins are insoluble or swellable in a high-insulating
non-aqueous solvent and do not spontaneously disperse to form
grains. In contrast to this resins, it has been found that
graft-copolymers of a certain kind, which are composed of a
component insoluble in a carrier liquid and a component soluble in
a carrier liquid, may spontaneously disperse in the carrier liquid
to form grains therein as if they dissolve therein, simply by
merely adding them to the carrier liquid. However, random
copolymers which are composed of the same insoluble component and
soluble component are either insoluble or swellable in a carrier
liquid but they do not display a despersibility behavior. Though it
is not clear at present why the graft-copolymers of the present
invention display the behavior, it is presumed that the insoluble
component in the graft-copolymer forms nuclei of the grains while
the soluble component in the graft-copolymer is solvated with the
carrier liquid to thereby maintain a stable dispersion of the
grains in the carrier liquid.
The graft-copolymer of the present invention has been achieved by a
copolymer obtained by copolymerization of macromonomers and
copolymerizable comonomers. The copolymer thus prepared is a graft
copolymer where the branches are derived from the macromonomers and
the stem from the comonomers (macromonomer method).
In a general graft-copolymerization reaction where no macromonomer
is present, a stem polymer which has a graft-copolymerizable
graft-active point is first synthesized and it is then
copolymerized with comonomers as branches. The above-mentioned
macromonomer method is opposite to the general
graft-copolymerization method where the stem polymer is first
synthesized and then it is copolymerized with comonomers as
branches.
In general, graft-copolymers which are produced using the
macromonomer method have the following advantages.
(1) Production of only a small amount of homopolymers composed of
only branch components or stem components occurs. Accordingly, the
purity of the graft-copolymer to be prepared is high.
(2) Control of the molecular weight of the branch moieties, the
molecular weight of the total graft-copolymer and the proportion of
the branch moieties and the stem moiety is easy.
(3) By varying the combination of the branch components and the
stem components, molecular planning to produce the desired
copolymers may freely be effected.
(4) It is known that the reactivity rate in copolymerization of
preparing macromonomers is the same as the reactivity rate of the
corresponding monomers. Therefore, copolymerization in preparing
macromonomers may be effected in the same manner as the general
polymerization of monomers.
The graft-copolymers for use in the present invention can easily be
prepared using the macromonomer method, where the moieties to be
branches are macromonomerized and then copolymerized with the
comonomer components. The components to be macromonomerized may be
either those of the grains (or components which are insoluble in a
carrier liquid) or those to be solvated (or components which are
soluble in a carrier liquid). Accordingly, the copolymerizing
comonomers are selected from solvating monomers when the
macromonomers are components to form grains, while monomers to form
grains are selected when the macromonomers are solvating
components. Two or more kinds of comonomers may be employed in
combination, if desired.
Examples of macromonomers and comonomers forming components which
are insoluble in a carrier liquid and components soluble in the
same include vinyl group-containing monomers, as well as monomers
having a polycondensable or polyaddable functional group, such as a
carboxyl group, a hydroxyl group, an amino group, an isocyanate
group, an epoxy group or an acid anhydride containing group. Above
all, vinyl group-containing monomers are advantageous.
In the monomers, those to form components which are insoluble in
the carrier liquid are, as examples, represented by the following
general formula (1), and those to form components which are soluble
in the carrier liquid are as examples, represented by the following
general formula (2). ##STR1## wherein R.sub.1 represents a hydrogen
atom or a methyl group; and R.sub.2 represents --COOR.sub.3,
--O--COR.sub.3, ##STR2## or CN.
In these groups, R.sub.3 represents a substituted or unsubstituted
alkyl group having from 1 to 3 carbon atoms, a cycloalkyl group
having from 3 to 8 carbon atoms, or a residue of a crosslinked
hydrocarbon compound.
Examples of substituents for the alkyl group are a hydroxyl group,
a halogen atom (e.g., chlorine, bromine, fluorine), a cyano group,
and an alkoxy group having from 1 to 3 carbon atoms. The
crosslinked hydrocarbon compounds are preferably those having from
4 to 18 carbo n atom s (e.g ., adamantane bicyclo(3,2,1)octane,
bicyclo(5,2,0) nonane, bicyclo(4,3,2)undecane).
R.sub.4 represents a hydrogen atom, an alkyl group having from 1 to
4 carbon atoms, a halogen atom (e.g., chlorine, bromine, fluorine),
a nitro group, a cyano group or a hydroxyl group. The number of the
substituent R.sub.4 's on the phenyl group may be from 1 to 3.
n represents from 0 to 2; and m represents 0 or 1.
R.sub.5 represents a hydrogen atom, a methyl group, an ethyl group,
a halogen atom (e.g., chlorine, bromine, fluorine), a nitro group,
a cyano group or a hydroxyl group. The number of the substituents
R.sub.5 's on the phenyl group may be from 1 to 3.
n represents from 0 to 2.
R.sub.6 and R.sub.7 may be same or different and each represents an
alkyl group having from 1 to 4 carbon atoms.
Specific examples of monomers which can be used are methyl
acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate,
n-propyl methacrylate, isopropyl methacrylate, trifluoromethyl
methacrylate, 3-chloro-2-hydroxypropyl methacrylate, cyclopropyl
acrylate, cycloheptyl acrylate, cyclopropyl methacrylate,
cycloheptyl methacrylate, cyclohexyl acrylate, cyclooctyl acrylate,
cyclooctyl methacrylate, vinyl acetate, vinyl propionate, vinyl
chloroacetate, ethoxymethyl methacrylate, methoxyethyl
methacrylate, isobromyl methacrylate, adamantyl methacrylate,
2-hydroxyethyl methacrylate, 2-phenoxyethyl methacrylate, benzyl
acrylate, benzyl methacrylate, p-methylbenzyl methacrylate, vinyl
benzoate, vinyl-p-methylbenzoate, vinyl p-isopropyl, benzoate,
vinyl-p-t-butylbenzoate, styrene, p-methylstyrene, p-chlorostyrene,
p-nitrostyrene, acrylo-nitrile, methacrylonitrile,
N,N-dimethylacrylamide and N,N-dimethylmethacrylamide.
Of these monomers, preferred monomers are methacrylates such as
methyl methacrylate, ethyl methacrylate, cyclohexyl methacrylate
and benzyl methacrylate as well as styrene and p-methylstyrene.
##STR3## wherein R.sub.1 represents a hydrogen atom or a methyl
group; and R.sub.8 represents --COOR.sub.9, --O--COR.sub.9,
--OR.sub.9, ##STR4##
In these groups, R.sub.9 represents a linear or branched
substituted or unsubstituted alkyl group having from 6 to 22 carbon
atoms. Examples of substituents on the alkyl group are a hydroxyl
group, a halogen atom (e.g., chlorine, bromine, fluorine), a phenyl
group, a cyano group and a nitro group.
R.sub.10 represents a linear or branched substituted or
unsubstituted alkyl group having from 4 to 12 carbon atoms.
Examples of substituents on the alkyl group include those mentioned
above.
l represents from 0 to 6; and m represents 0 or 1:
Specific examples of suitable monomers include n-hexyl acrylate,
n-hexyl methacrylate, n-heptyl methacrylate, n-octyl acrylate,
n-octyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl
methacrylate, n-decyl acrylate, n-decyl methacrylate,
isodecylmethacrylate, n-dodecyl acrylate, n-dodecyl methacrylate,
isodecyl methacrylate, isostearyl methacrylate, stearyl
methacrylate, behenyl methacrylate, vinyl caprate, vinyl laurate,
vinyl stearate, vinyl behenate, vinyl-n-hexyl ether,
vinyl-2-ethylhexyl ether, vinyl-dodecyl ether, vinyl-stearyl ether,
p-2-ethylhexylbenzyl methacrylate, p-n-butylstyrene and
p-2-ethylhexyl styrene.
Among these compounds, preferred are long-chain alkyl
(meth)acrylates such as n-octyl methacrylate, n-octyl acrylate,
2-ethylhexyl methacrylate, dodecyl methacrylate, dodecyl acrylate
and stearyl methacrylate.
In accordance with the present invention, macromonomers are
employed as components of either soluble monomers or insoluble
monomers of the graft copolymers for use in the invention. The
methods described, for example, in Y. Kawakami & Y. Yamashita,
Chemistry, Vol. 37, No. 8, page 588 (1982); P.F. Rempp & E.
Franta, Advanced Polymer Science, Vol. 58, No. 1 (1984); K. Itoh,
Processing of High Polymers, Vol. 35, No. 6, page 262 (1986); P.
Dryfuses & R.P. Quirk, Encycl Polym. Sci. Eng., 7, 551 (1987);
V. Percec, Appl. Polym. Sci., 285, 95 (1984); R. Asami & M.
Takaki, Makromol. Chem. Suppl., 12, 163 (1985); P. Rempp, et al,
Makromol. Cheml. Suppl., 8, 3 (1984); Y. Kawakami, Chemical
Industry, 38, 56 (1987); Y. Yamashita, High Polymers, 31,
988(1982); S. Kobayashi, High Polymers, 30, 625 (1981); To. Tomura,
Journal of Japan Adhesive Association, 18, 536 (1982); and S. Tohki
& T. Tsuda, Functional Materials, No. 10, 5 (1987) for
producing macromonomers to be used in the invention.
For producing macromonomers having a polymerizable terminal double
bond, the following methods can be employed.
(1) A double bond is introduced into the polymer terminal by a
polymerization reaction, using a double bond-containing initiator
or stopper.
(2) A prepolymer having a terminal functional group is produced
using a chain-transferring agent or stopper having an appropriate
functional group, and the functional group of the resulting
prepolymer is then reacted with a double bond-containing compound
to introduce a double bond into the polymer terminal.
(3) A bi-functional vinyl monomer and a bi-functional compound are
reacted in a polyaddition reaction, whereupon the polyaddition
reaction is controlled so as to keep a non-reacted vinyl group at
the terminal of the resulting polymer.
The macromonomers for use in the present invention preferably have
a molecular weight of from 1,000 to 5,000, more preferably from
2,000 to 20,000, as a number average molecular weight based on
polystyrene by GPC method.
Methods of production are described below in more detail.
EXAMPLES AND METHOD (1)
A living polymer of polystyrene is reacted with p-vinylbenzyl
chloride to produce a terminal styrene-type polystyrene
macromonomer in accordance with the following: ##STR5##
Bu=butyl, hereinafter the same
Alternatively, a different method can be used where the reactant is
reacted with ethylene oxide in the course of the reaction to form a
terminal alkoxide for endocapping and thereafter the intermediate
is reacted with methacryloyl chloride, as follows: ##STR6##
EXAMPLES OF METHOD (2)
An acrylic monomer is radical-polymerized in the presence of a
mercaptan-type chain-transferring agent to produce a macromonomer,
as follows: ##STR7##
In the polymerization to obtain macromonomers for use in the
present invention, the living polymerization method (1) or the
radical polymerization method (2) can be employed. The former
method may be used to produce macromonomers having a uniform
molecular weight polymerization, but control of polymerization
reaction in the method is difficult. On the other hand, although
the latter method is inferior to the former method in terms of the
uniformity of the molecular weight distribution of the
macromonomers obtained, it is industrially practicable since the
reaction itself is easy.
Where a bi-functional compound is used as a chain-transferring
agent in method (2), one-terminal carboxylic acid/diol
macromonomers are obtained and they can be utilized for preparing
graft-copolymers of polyesters or polyurethanes. ##STR8##
Specific examples of macromonomers which can be used to form the
graft-copolymers of the present invention are described below,
which, however, are not to be construed as limiting the present
invention. ##STR9##
Commercial products can be used as these macromonomers.
For example, these macromonomers commercial products are available
as from Satomer Co., Toa Gosei Chemical Industry Co., Soken
Chemical Co., and Nippon Oils & Fats Co.
Some examples of commercial macromonomers which can be used in the
present invention are described below. These are commercially
available from Toa Gosei Chemical Industry Co.
______________________________________ Molecular Trade Terminal
Group Segment Weight Name ______________________________________
Methacryloyl Styrene 6000 AS-6 ##STR10## Styrene/Acrylonitrile
Methyl Methacrylate Butyl 6000 6000 6000 AN-6 AA-6 AB-6 Silicone
5000 AK-6 Dicarboxyl Styrene 6000 CS-6 ##STR11##
Styrene/Acrylonitrile Butyl Acrylate 6000 6000 CN-6 CB-6 Dihydroxyl
Styrene 6000 HS-6 ##STR12## Styrene/Acrylonitrile Methyl
Methacrylate 6000 6000 HN-6 HA-6
______________________________________ Molecular Weight: Number
Average Molecular Weight by the GPC method
Graft-copolymers for use in the present invention may be prepared
from the macromonomers by copolymerization such as by addition
polymerization, by polycondensation or by polyaddition with
appropriate comonomers.
It is considered that a macromonomer is a kind of a monomer and it
is known that they are little different in the reactivity.
Accordingly, it is considered that the synthesis of a graft
copolymer from a macromonomer is the same as that in usual
polymerization reaction. In a case of addition polymerization
(radical polymerization), it is possible to apply all
polymerization method such as a bulk polymerization, a solution
polymerization, a suspension polymerization, and an emulsion
polymerization. Usually, a solution polymerization is applied. It
is disclosed, for example, in G. O. Schulz, R. Milkovich; J. Polym.
Sci., Polym. Ed., 22, 1633 (1984), J.C.J.F. Tacx, H.N. Linssen, A.
L. German; J. Polym. Sci.; Part A: Polym. Chem. 26, 61 (1988). As
an initiator, there are, for example, azobis compounds (e.g.,
AIBN), peroxides (e.g., benzyl peroxide), redox initiators (e.g.,
persulfate, NaHSO.sub.3)
Two or more macromonomers can be used in combination, provided that
they are copolymerizable. Additionally, two or more copolymerizing
comonomers may also be used in combination.
In particular, terminal vinyl group-having macromonomers are
advantageously used as they may easily be polymerized with vinyl
group-having comonomers by radical polymerization.
Any known initiators for radical polymerization can be
employed.
The graft-copolymers for use in the present invention preferably
have a molecular weight of from 3,000 to 500,000, more preferably
from 10,000 to 200,000, as a number average molecular weight
measured by the GPC method.
The proportion of the component which is insoluble in a carrier
liquid to that which is soluble in the carrier liquid in the
graft-copolymer for use in the present invention can vary but is
generally so selected that the graft-copolymer is substantially
insoluble in the carrier liquid. In general, therefore, the
proportion of the insoluble component to the soluble component is
from 30/70 to 99/1, preferably from 40/60 to 95/5, by weight.
The term "substantially insoluble graft-copolymer" means that when
a 5 wt % solution of the graft-copolymer is subjected to
centrifugation at 15,000 rpm for 60 minutes, the precipitate
(corresponding to grains in the solution)is 30% by weight or more
to the total weight.
Although not completely clear, the reason why the graft-copolymer
of the present invention is self-dispersible is believed to be as
follows. The graft-copolymer which is composed of a component
insoluble in a carrier liquid and a component soluble in the
carrier liquid is present in the carrier liquid in the form of
micelles where the insoluble parts are oriented toward the inside
and the soluble parts are oriented toward the outside. Where the
insoluble parts are present in an amount larger than that of the
soluble parts, the micelles consist essentially of grains. In the
opposite case, the micelle is a soluble one. The graft-copolymer of
the present invention, which is prepared from the above-mentioned
macromonomers, contains only a small amount of homopolymers and
other impurities, as mentioned above. Therefore, it is believed
that the graft-copolymer of the invention displays this intrinsic
property, even though it is in a solid form.
In the present invention, a non-aqueous solvent having an
electrical resistance of 1.times.10.sup.9 .OMEGA.cm or more and a
dielectric constant of 3 or less is used as a carrier liquid.
Examples of suitable non-aqueous solvents, for example, include
solvents of linear or branched aliphatic hydrocarbons, alicyclic
hydrocarbons, aromatic hydrocarbons and halogenated hydrocarbons.
Considering low vaporizability, high safety, low environmental
pollution and low odor, octane, isooctane, decane, isodecane,
dodecane, isododecane, nonane, isoparaffin petroleum solvents of
Isopar E, Isopar G, Isopar H and Isopar L (trade names of the Exxon
Co.), as well as Isododecane (BP Chemical), Shell Sol 71 (Shell),
and IP Sorbent 1620 (Idemitsu Petrochemical) are preferred.
Various known inorganic pigments, organic pigments and dyes can be
used as the pigment or dye for use in the present invention.
For instance, usable pigments and dyes include metal powders such
as aluminium powder; metal oxides such as magnetic iron oxide, zinc
oxide, titanium oxide or silicon dioxide; metal salts such as
powdery lead cadmium-selenium-chromate; as well as Vulcan Fast
Yellow (C.I. 21095, C.I. 21220), Hansa Yellow (C.I. 11680, C.I.
11730, C.I. 11710), Benzidine Yellow (C.I. 21090, C.I.21100),
Benzidine Orange (C.I. 21110), Fast Red (C.I. 37085, C.I. 37120,
C.I. 37275), Brilliant Carmine 3B (C.I. 16015-Lake), Brilliant
Carmine 6B (C.I. 15850), Phthalocyanine Blue (C.I. 74160), Heliogen
Blue (C.I. 74100), Threne Blue (C.I. 69800), Phthalocyanine Green
(C.I. 74260), Victoria Blue (C.I. 42595-Lake), Spirit Black (C.I.
50415), Oil Blue (C.I. 74350), Alkali Blue (C.I. 42770A), Fast
Scarlet (C.I. 12315), Rhodamine 6B (C.I. 45160), Fast Sky Blue
(C.I. 74200-Lake), Nigrosene (C.I. 50415), and carbon black.
Additionally, surface-treated pigments, for example, nigrosene-dyed
carbon black or graft carbon prepared by graft-polymerization of
carbon and a polymer, may also be used.
Any known charge-adjusting agent may be incorporated into the
liquid developing agent of the present invention. For instance,
substances usable as a charge-adjusting agent include metal salts
of fatty acids such as naphthenic acid, octenoic acid, oleic acid
or stearic acid; metal salts of sulfosuccinates; oil-soluble metal
salts of sulfonic acid, as described in JP-B-45-556, JP-A-52-37435
and JP-A-52-37049; metal salts of phosphates, as described in
JP-B-45-9594; metal salts of abietic acids or hydrogenated abietic
acids, as described in JP-B-48-25666; calcium salts of
alkylbenzenesulfonic acids, as described in JP-B-55-2620; metal
salts of aromatic carboxylic acids or sulfonic acids, as described
in JP-A-52-107837, JP-A-52-38937, JP-A-57-90643 and JP-A-57-139753;
nonionic surfactants such as polyoxyethylated alkylamines; fats and
oils such as lecithin or linseed oil; polyvinyl pyrrolidones;
organic acid esters with polyhydric alcohols; phosphate surfactants
as described in JP-A-57-210345; and sulfonic acid resins as
described in JP-B-56-24944. Additionally, amino acid derivatives as
described in JP-A- 60-21056 and JP-A-61-50951 may also be employed.
These amino acid derivatives are compounds of the following formula
(3) or (4), or a reaction mixture prepared by reacting an amino
acid with a methane compound in an organic solvent followed by
further reaction of the reaction mixture with water. ##STR13##
In these formulae, R.sub.11 and R.sub.12 each represent a hydrogen
atom, an alkyl group having from 1 to 22 carbon atoms, a
substituted alkyl group having from 1 to 22 carbon atoms (e.g.,
substituted with a dialkylamino group, an acyloxy group or an
alkylthio group), an aryl group having from 6 to 24 carbon atoms, a
substituted aryl group having from 6 to 24 carbon atoms (e.g.,
substituted with a dialkylamino group, an alkyloxy group, an
alkylthio group, a chlorine atom, a bromine atom, a cyano group, a
nitro group, or a hydroxyl group), an aralkyl group having from 6
to 24 carbon atoms, an acyl group having from 1 to 22 carbon atoms,
an alkylsulfonyl group having from 1 to 22 carbon atoms, an
alkylphosphonyl group having from 1 to 22 carbon atoms, an
arylsulfonyl group having from 6 to 24 carbon atoms, or an
arylphosphonyl group having from 6 to 24 carbon atoms. R.sub.11 and
R.sub.12 may be same as Or different from each Other. R.sub.11 and
R.sub.12 may combine and form a ring, but R.sub.11 and R.sub.12 are
not simultaneously hydrogen atoms. A represents an alkylene or
substituted alkylene group having from 1 to 10 carbon atoms. X
represents a hydrogen atom, or a mono- to tetra-valent metal (e.g.,
Na, K, Ca, Mg, Al, Fe, Co, Ni, Zn, Mn, Ti), or a quaternary
ammonium ion. n represents a positive integer.
Additionally, quaternatry amine polymers is described in
JP-A-54-31739 and JP-B-56-24944 may also be used.
Above all, preferred examples are metal salts of naphthenic acid,
metal salts of dioctylsulfosuccinic acid and the above-described
amino acid derivatives. Further preferred are zirconium, cobalt or
manganese naphthenate, calcium or sodium dioctylsulfosuccinate and
metal salts of the compounds of formula (3) described above.
Titanium, cobalt, zirconium and nickel salts thereof are especially
preferred as metal salts of the compounds of formula (3) above.
In order to increase the dispersibility of the self-dispersible
solid colorant of the present invention and to increase the
stability of the dispersion of the colorant, a dispersing agent may
be applied to the colorant. The dispersing agent to be used for the
purpose is a resin which is soluble in a carrier liquid and which
is adsorbed on the toner grains to thereby improve the
dispersibility of the grains. Examples of suitable dispersing
agents are rubbers such as styrene-butadiene,
vinyltoluene-butadiene or butadiene-isoprene; polymers of acrylic
monomers having a long-chain alkyl group, such as 2-ethylhexyl
(meth)acrylate, lauryl (meth)acrylate or stearyl (meth)acrylate;
copolymers of these acrylic monomers with other monomers (e.g.,
styrene, (meth)acrylic acid and the methyl, ethyl or propyl ester
thereof); and macromonomer-grafted graft-copolymers as described in
Japanese Patent Application No. 1-253252.
The dispersing agent may be added to the self-dispersing colorant
or it may previously be added to a carrier liquid.
Methods of preparing the self-dispersing colorant, toner supply and
toner kit of the present invention are described in detail
below.
When the self-dispersing graft-copolymer of the invention is used
as a dispersion of resin grains, it can be used in the form of a
mass, tablet or powder. A colorant comprising the graft-copolymer
and a pigment or dye may be prepared using the methods described
below.
(1) The graft-copolymer is melt-kneaded with a pigment or dye at a
temperature higher than the softening point of the graft-copolymer
using a roll mill, Bumbury mixer or kneader and then optionally
powdered. The kneaded blend or powder is then formed into a mass,
tablets, granules or a powder.
(2) The graft-copolymer is dissolved in a solvent, a pigment or dye
is added thereto and wet-dispersed using a ball mill, attritor or
sand grinder. Then the solvent is evaporated from the blend to
obtain the desired colorant. Alternatively, the resulting
dispersion is poured into a non-solvent for the graftcopolymer to
obtain a mixed blend, which is then dried to obtain a colorant.
(3) In a flashing method, a hydrous paste of a pigment is kneaded
along with a resin or a resin solvent, and the water in the
resulting mix is replaced by a resin or a resin solution. Then, the
water or solvent is removed by drying (under reduced pressure) to
obtain an intended colorant.
For preparing a toner supply for a liquid developing agent for
electrostatic photography, a charge-adjusting agent or a dispersing
agent is added to the copolymer during kneading, or is added
thereto during powdering of the tablets obtained from the kneaded
mix.
The carrier liquid may be used as it is when the carrier liquid is
used alone as the carrier liquid for the toner kit of the present
invention. If the carrier liquid contains a charge-adjusting agent
or a dispersing agent, necessary amount of these agents may be
added to the carrier liquid.
In the colorant of the invention, the proportion of the
graft-copolymer to the pigment or dye is from 0.1/1 to 100/1,
preferably from 0.3/1 to 30/1, by weight.
The amount of the charge-adjusting agent in the liquid developing
agent of the invention is preferably from 0.001 to 10 g, more
preferably from 0.01 to 3 g, per liter of the carrier liquid in the
agent.
Where the colorant contains a dispersing agent, the amount of the
agent therein is preferably from 0.001 to 20 parts by weight, more
preferably from 0.03 to 10 parts by weight, to one part by weight
of the graft-copolymer. Where a dispersing agent is present in a
carrier liquid, the amount of the agent is preferably from 0.01 to
50 g, more preferably from 0.1 to 20 g, per liter of the carrier
liquid.
The amount of the toner grains in the liquid developing agent of
the invention can vary, but preferably is from 0.01 to 50 g, more
preferably from 0.1 to 20 g, per liter of the carrier liquid in the
agent.
Any known organic photoconductor or inorganic photoconductor may be
employed as a photoreceptor to be used in the present invention.
Additionally, a dielectric charged with a charging needle may also
be used.
Suitable organic photoconductor which can be employed with the
present invention include known photoconductors. For example, the
materials described in Research Disclosure No. 10938 (May, 1973,
from page 61 on, report with a title of Electrophotographic
Elements, Materials and Processes can be used.
Examples which are now practically used and which may be employed
with the present invention are, for example, an electrophotographic
photoreceptor composed of polyvinyl-N-carbazole and
2,4,7-trinitrofluoren-9-one (U.S. Pat. No. 3,484,237);
poly-N-vinylcarbazole sensitized with a pyrylium salt dye
(JP-B-48-25658): an electrophotographice photoreceptor consisting
essentially of an organic pigment (JP-A-49-543); an
electrophotographic photoreceptor consisting essentially of an
eutectic complex composed of a dye and a resin (JP-A-47-10735); and
an electrophotographic photoreceptor comprising copper
phthalocyanine dispersed in a resin (JP-B-52-1667). Additionally,
the materials described in Journal of Japan Electrophotographic
Society, Vol. 25, pages 62 to 76 may also be used.
Examples of inorganic photoconductors which may be employed with
the present invention include various inorganic compounds as
described in R. M. Schaffert, Electrophotography (published by
Focal Press, London, 1975), pages 260 to 374 are typical. Specific
examples include zinc oxide, zinc sulfide, cadmium sulfide,
selenium selenium-tellurium alloy, selenium-arsenic alloy, and
selenium-tellurium-arsenic alloy.
Examples of the present invention are described below, which,
however, are not intended to limit the scope of the present
invention. Unless otherwise indecated, all parts, percents, ratios
and the like are by weight.
Production of Macromonomer (1):
A mixture comprising 92 g of methyl methacrylate, 6 g of
thioglycolic acid and 220 g of toluene was heated to 75.degree. C.
with stirring under a nitrogen atmosphere. Next, 31 g of
2,2'-azobis (cyanovaleric acid) (A.C.V.) was added thereto and
reacted for 8 hours. Next, 8 g of glycidyl methacrylate, 1.0 g of
N,N-dimethyldodecylamine and 0.5 g of t-butylhydroquinone were
added to the reaction mixture and stirred at a temperature of
100.degree. C. for 12 hours. After cooling, the reaction mixture
was re-precipitated in 3 liters of methanol to obtain 82 g of a
white powder. The polymer thus prepared had a number average
molecular weight of 6,000.
PRODUCTION OF MACROMONOMER (2)
A mixture comprising 93 g of dodecyl methacrylate, 8 g of
3-mercaptopropionic acid, 200 g of toluene and 30 g of isopropanol
was heated to 70.degree. C. under a nitrogen atmosphere to obtain a
uniform solution. 1.0 g of azo-bis-isobutyronetrile (A.I.B.N.) was
added thereto and reacted for 12 hours. After cooling, the reaction
solution was re-precipitated in 2 liters of methanol and then
heated at a temperature of 50.degree. C. under reduced pressure to
remove the solvent by distillation. The thus obtained viscous
product was dissolved in 200 g of toluene; and 16 g of glycidyl
methacrylate, 1.0 g of N,N-dimethyldodecyl methacrylate and 1.0 g
of t-butylhydroquinone were added to the resulting solution and
thereafter stirred at a temperature of 110.degree. C. for 10 hours.
The resulting reaction solution was again reprecipitated in 2
liters of methanol. A pale yellow viscous product was obtained,
which had a number average molecular weight of 4,000.
PRODUCTION OF GRAFT-COPOLYMER (1)
A graft-copolymer (1) was prepared, using a styrene macromonomer
(AS-6, commercially available from Toa Gosei Chemical Industry
Co.).
Specifically, 90 g of AS-6, 10 g of stearyl methacrylate and 200 g
of toluene were put in a 500 ml-four neck flask equipped with a
stirrer, a thermometer, a condenser and a nitrogen gas inlet, and
they were heated and stirred therein at 80.degree. C. for 1 hour
while introducing nitrogen gas. Next, 1 g of a polymerization
initiator of 1,1'-azobis(1-cyclohexanecarbonitrile) was added to
the mixture and the resulting mixture was polymerized at 80.degree.
C. for 24 hours. After the polymerization, the reaction mixture was
cooled to room temperature, and 200 g of toluene was added thereto.
This was then re-precipitated in 4 liters of methanol. The
resulting re-precipitate was then washed several times with
methanol and dried in vacuum. Accordingly, a white powdery solid
was obtained.
PRODUCTION OF GRAFT-COPOLYMERS (2) to (9)
Graft-copolymers (2) to (9) described below were prepared in the
same manner as in the preparation of Graft-copolymer (1).
PRODUCTION OF GRAFT-COPOLYMER (1)
80 g of Macromonomer (1) as prepared in Example 1, 20 g of stearyl
methacrylate and 200 g of toluene were put in a 500 ml-four neck
flask equipped with a stirrer, a thermometer, a condenser and a
nitrogen gas inlet and they were heated and stirred therein at
70.degree. C. for 1 hour while introducing nitrogen gas. Next, 1.0
g of a polymerization initiator of 2,2'-azobisbutyronitrile was
added to the mixture so that the resulting mixture was polymerized
at 70.degree. C. for 24 hours. After polymerization, the reaction
mixture was cooled to room temperature, and 200 g of toluene was
added thereto. This was then re-precipitated in 4 liters of
methanol. The resulting re-precipitate was then washed several
times with methanol and dried in vacuum. Accordingly, a white
powdery solid was obtained.
Macromonomers and comonomers used for preparing the above-mentioned
graft-copolymers, the molecular weight of each of the
graft-copolymers formed, as well as the self-dispersibility of each
graft-copolymer when added to a carrier liquid comprising Isopar G
and the size of the dispersed grains thereof in Isopar G are shown
in Table 1 below.
______________________________________ Graft- A/B Ratio Copolymer
Macromonomer (A) Comonomer (B) (by weight)
______________________________________ 2 AS-6 Stearyl 80/20
(styrene macro- Methacrylate monomer produced by Toa Gosei Chemical
Industry) 3 AS-6 Stearyl 70/30 (styrene macro- Methacrylate monomer
produced by Toa Gosei Chemical Industry) 4 AS-6 Stearyl 50/50
(styrene macro- Methacrylate monomer produced by Toa Gosei Chemical
Industry) 5 AS-6 Lauryl 70/30 (styrene macro- Methacrylate monomer
produced by Toa Gosei Chemical Industry) 6 AS-6 2-Ethylhexyl 70/30
(styrene macro- Methacrylate monomer produced by Toa Gosei Chemical
Industry) 7 AA-6 Stearyl 80/20 (methyl meth- Methacrylate acrylate
macro- monomer produced by Toa Gosei Chemical Industry) 8 AA-6
Lauryl 80/20 (methyl meth- Methacrylate acrylate macro- monomer
produced by Toa Gosei Chemical Industry) 9 AA-6 2-Ethylhexyl 80/20
(methyl meth- Methacrylate acrylate macro- monomer produced by Toa
Gosei Chemical Industry) ______________________________________
TABLE 1
__________________________________________________________________________
Graft-Copolymers Content of Grain A/B Ratio Molecular
Grains.sup.(2) Size.sup.(3) No. Macromonomer (A) Comonomer (B) (by
weight) Weight.sup.(1) (%) (.mu.) Self-Dispersibility.sup.(4)
__________________________________________________________________________
1 AS-6 Stearyl 90/10 3.2 .times. 10.sup.4 98 0.10 Clouded, and
Methacrylate partly precipitated. 2 " Stearyl 80/20 3.4 .times.
10.sup.4 93 0.13 Clouded, but Methacrylate not precipitated. 3 "
Stearyl 70/30 3.5 .times. 10.sup.4 72 0.14 Clouded, but
Methacrylate not precipitated. 4 " Stearyl 50/50 4.1 .times.
10.sup.4 32 0.20 Clouded, but Methacrylate not precipitated. 5 "
Lauryl 70/30 3.5 .times. 10.sup.4 71 0.13 Clouded, but Methacrylate
not precipitated. 6 " 2-Ethylhexyl 70/30 3.6 .times. 10.sup.4 74
0.12 Clouded, but Methacrylate not precipitated. 7 AA-6 Stearyl
80/20 3.2 .times. 10.sup.4 90 0.10 Clouded, but Methacrylate not
precipitated. 8 " Lauryl 80/20 3.3 .times. 10.sup.4 88 0.11
Clouded, but Methacrylate not precipitated. 9 " 2-Ethylhexyl 80/20
3.2 .times. 10.sup.4 92 0.10 Clouded, but Methacrylate not
precipitated. 10 Macromonomer (1) Stearyl 80/20 1.8 .times.
10.sup.4 81 0.11 Clouded, but Methacrylate not precipitated.
__________________________________________________________________________
.sup.(1) Molecular Weight: number average molecular weight based on
polystyrene, measured by GPC. .sup.(2) Content of Grains: Amount
(wt %) of precipitate as precipitated by centrifugation in Isopar G
(5 wt %) dispersion at 1500 rpm for 1 hour. .sup.(3) Grain Size:
measured with a Nanosizer (manufactured by Nikkaki). .sup.(4)
SelfDispersibility: behavior of graftcopolymer grains in Isopar
G.
PRODUCTION OF COMPARATIVE COPOLYMERS (1) to(4)
Comparative copolymers (1) to(4) described below were prepared,
using monomers in general in place of macromonomers.
Specifically, 90 g, 80 g, 70 g of styrene, 10 g, 20 g, 30 g or 50 g
of stearyl methacrylate and 200 g of toluene were subjected to
polymerization in the same manner as in preparation of
Graft-copolymer (1) to prepare Comparative Copolymers (1) to (4),
respectively. These copolymers were all random copolymers, which
are shown in Table 1' below.
TABLE 1'
__________________________________________________________________________
Comparative A/B Ratio Molecular Copolymer Monomer (A) Monomer (B)
(by weight) Weight.sup.(1) Solubility.sup.(2)
__________________________________________________________________________
1 Styrene Stearyl Methacrylate 90/10 2.3 .times. 10.sup.4 15%
swollen 2 " " 80/20 2.6 .times. 10.sup.4 25% swollen 3 " " 70/30
3.0 .times. 10.sup.4 75% almost dissolved 4 " " 50/50 3.3 .times.
10.sup.4 100% dissolved
__________________________________________________________________________
.sup.(1) Molecular Weight: number average molecular weight by GPC.
.sup.(2) Solubility: Amount dissolved in Isopar (5 wt %).
None of the Comparative Copolymers (1) to (4) were self-dispersed
in Isopar G but dissolved therein. It is clear that the properties
of these Comparative Copolymers (1) to (4) are different from the
graft-copolymers of the present invention prepared by the
macromonomer method.
EXAMPLE 1
20 g of Graft-copolymer (2) was dissolved in 100 g of toluene, and
5 g of Carbon Black #30 (manufactured by Mitsubishi Kasei Corp.)
was added thereto and dispersed for one hour using a paint shaker.
The resulting dispersion was dried on a stainless steel vat and
then dried at 50.degree. C in vacuum. The dried
graft-copolymer/carbon black colorant was powdered in a sample mill
(manufactured by Kyoritsu Rika Co.). Each of the powdered colorant
(0.1 to 0.01 mm) and the non-powdered colorant (1 to 5 mm) was
placed in Isopar G (isoparaffin hydrocarbon solvent, manufactured
by Exxon Co.) and self-dispersibility was evaluated. As a result,
both colorants were well self-dispersed in the solvent to produce
stably dispersed grains. In both cases, the colorant spontaneously
self-dispersed in the solvent after it was left as it was in the
solvent without stirring.
TABLE 2 ______________________________________ Self- Grain Size of
Colorant Size Dispersibility Dispersed Grains
______________________________________ Pinmill 0.1 to
Self-dispersed 0.32 micron Powdered 0.01 mm within 6 hours Non- 1
to Self-dispersed 0.31 micron powdered 5 mm in one day
______________________________________
In the self-dispersion test, 1 g of the colorant to be tested was
added to 50 g of Isopar G and was then left at it was. Afterwards,
the dispersion condition of the resulting dispersion was
evaluated.
EXAMPLES 2 TO 4
Other black colorant dispersions were prepared in the same manner
as in Example 1, except that Graft-copolymer (1), (3) or (4) was
used. These were tested in the same manner as in Example 1, and the
results obtained are shown in Table 3 below.
TABLE 3 ______________________________________ Size of Grain Size
Ex. Graft- Powdered Self of Dispersed No. Copolymer Colorant
Dispersibility Grains ______________________________________ 2 (1)
0.1 to Almost self- 0.52 micron 0.01 mm dispersed within one day,
but some non-dispersed precipitate remained 3 (3) 0.1 to Completely
self- 0.30 micron 0.01 mm dispersed within 3 hours, with no
non-dispersed precipitate. 4 (4) 0.1 to Completely self- 0.32
micron 0.01 mm dispersed within 3 hours, with no non-dispersed
precipitate. ______________________________________
As mentioned above, the colorant containing Graft-copolymer (1) was
dispersed in one day, but some non-dispersed precipitate remained.
However, the others all self-dispersed within 30 minutes.
EXAMPLE 5
4 parts of Graft-copolymer (2) and one part of Carbon Black #30
were melt-kneaded with a three-roll kneader heated at 120.degree.
C. for 30 minutes to obtain a black colorant.
This was powdered in the same manner as in Example 1 and then added
to Isopar G, whereupon it self-dispersed therein within 6 hours to
provide stably dispersed grains having a grain size of 0.35
micron.
EXAMPLES 6 TO 10
Other black colorants were prepared in the same manner as in
Example 5, except that Graft-copolymers (5), (6), (7), (8) or (9)
was used.
TABLE 4 ______________________________________ Ex. Graft- No.
Copolymer Self-Dispersibility Grain Size
______________________________________ 6 (5) Self-dispersed within
6 hours. 0.33 micron 7 (6) " 0.45 micron 8 (7) " 0.47 micron 9 (8)
" 0.45 micron 10 (9) " 0.43 micron
______________________________________
As described above, all of the colorants were well self-dispersed
in the Isopar G solvent.
EXAMPLES 11 TO 13
Cyan, yellow and magenta coloring colorants were prepared in the
same manner as in Example 5, except that color pigments of copper
phthalocyanine (Pigment Blue 15, manufactured by Tokyo Kasei Co.),
disazo yellow (Pigment Yellow 14, manufactured by Toyo Ink Co.) and
Carmine 6B (Pigment Red 57-1, manufactured by Toyo Ink Co.) were
used, respectively, in place of Carbon Black #30. The
self-dispersibility of each colorant was evaluated and the results
are shown in Table 5 below. The formation of a powder of each
colorant was achieved using a pin mill, and the grain size of the
powdered colorant was from 0.1 to 0.01 mm.
TABLE 5 ______________________________________ Ex Grain Size of No.
Pigment Self-Dispersibility Dispersed Grains
______________________________________ 1 Copper Self-dispersed
within 0.34 micron Phthalo- half day (12 hours) cyaninea 2 Disazo
Yellow Self-dispersed within 0.47 micron half day (12 hours) 3
Carmine 6B Self-dispersed within 0.70 micron half day (12 hours)
______________________________________
As described above, all of the colorants were well self-dispersed
and formed clear dispersions. These dispersions were stable and no
noticeable precipitate was formed in one week or so.
EXAMPLE 14
10 parts of water and one part of carbon black (MA-100,
manufactured by Mitsubishi Kasei Corp.) were stirred in a flasher,
and 10 parts of Graft-copolymer (5) (as a 10% toluene solution) was
added thereto and further stirred. Next, the contents were heated
and the water and solvent were removed therefrom under reduced
pressure to obtain a colorant mass having a water content of 1% by
weight. A powder of this mass was produced in a sample mill to
obtain a colorant powder having a grain size of from 0.1 to 0.01
mm. (Prior to powdering, the colorant mass was dried in vacuum and
water was completely removed thereby.)
The self-dispersibility of the powder was educated in the same
manner as in Example 5. As a result, the powder was well
self-dispersed in the solvent in about one hour to provide
dispersed grains having a grain size of 0.32 micron.
EXAMPLE 15
The preparation of a toner supply and a toner kit for electrostatic
photography is illustrated below.
Specifically, the following components were kneaded using a
three-roll mill at 80.degree. C. for one hour.
______________________________________ Graft-Copolymer (2) 4 parts
Carbon Black #30 1 part (manufactured by Mitsubishi Kasei Corp.)
Isopar G 1 part Charge-Adjusting Agent 0.01 part ##STR14##
______________________________________
Next, the resulting mass converted to a powder with a sample mill
(manufactured by Kyoritsu Rika Co.) to a grain size of from 0.01 to
0.01 mm, whereupon the amount of Isopar G in the resulting powder
decreased to 1% by weight. A part of the powder was tabletted with
a tabletting machine into tablets, each having a diameter of 3
mm.
3 g of each of the powder and the tablets was added to one liter of
Isopar G. As a result, both forms were well dispersed in the
solvent to provide liquid developing agents comprising negative
polarity grains. Each of the liquid developing agents was employed
in a Panacopy KV-3000 (manufactured by Matsushita Electric Co.)
system, whereupon excellent images were formed with a high
resolving power and a high tone reproducibility.
TABLE 6 ______________________________________ Image
Self-Dispersibility Polarity Grain Size Quality
______________________________________ Powder Self-dispersed in
negative 0.30 micron good about 3 hours. Tablets Self-dispersed
negative 0.29 micron good after being left in solvent overnight.
______________________________________
The charge-adjusting agent-containing self-dispersing colorant
obtained above was combined with a carrier liquid to obtain a
self-dispersing toner kit.
The colorant powder obtained was added to used developer employed
above-described Panacopy KV-3000 system in an amount of 0.3 g per
100 ml of the developer, whereupon the powder self-dispersed in
several hours. The developer to which the powder had been added was
then used for development. The image density of the images obtained
increased from 0.3 to 1.5. Accordingly, it can be seen that the
colorant powder is effective as a toner supply.
Additionally, the liquid developing agent obtained above had a good
fixing properties. When it was used for development with Cassette
File 7000R (electronic file, manufactured by Fuji Photo Film Co.),
a good image-fixing property was displayed.
After the liquid developing agent obtained was allowed to stand for
a while, the toner grains hardly precipitated. The stored agent
still had an excellent re-dispersibility. Precisely, the agent
stored for 3 months under ambient conditions was easily
re-dispersed merely by shaking the container containing the
agent.
EXAMPLE 16
The following components were melt-kneaded with a three-roll mill
at 110.degree. C. for 30 minutes.
______________________________________ Graft-Copolymer (2) 4 parts
Carbon Black #30 1 part (manufactured by Mitsubishi Kasei Corp.)
Dispersing Agent (described below) 1 part
______________________________________
The kneaded blend was then converted into a powder with a sample
mill to obtain a powder having a grain size of from 0.3 to 0.01 mm.
Another kit was prepared using this powder. The Isopar G used
contained the same charge-adjusting agent as used in Example 15, in
an amount of 1.times.10.sup.-4 M/liter. When 3 g of the powder was
added to the charge-adjusting agent-containing Isopar G, it was
completely self-dispersed within about 30 minutes to produce a
negative polarity liquid developing agent. Development was effected
using this liquid developing agent in the same manner as in Example
15. Good images were formed with an excellent
image-reproducibility.
DISPERSING AGENT
A graft-copolymer of styrene macromonomer AS-6 and stearyl acrylate
(10/90) was dissolved in Isopar G, which was used as a dispersing
agent.
EXAMPLE 17
The following components were kneaded with a three-roll mill 2
hours at 80.degree. C.
______________________________________ Graft-Copolymer (7) 5 parts
Carbon Black #30 1 part Nigrosine (Bontron N-01 0.2 part
manufactured by Orient Chemical Co.) Zirconium Naphthenate 0.01
part Isopar G 1 part ______________________________________
The kneaded blend was then converted into a powder with a sample
mill to obtain a powder having a grain size of from 0.1 to 0.01 mm.
3 g of the powder was combined with one liter of Isopar G to
prepare a toner kit.
When the powder was added to Isopar G, it was self-dispersed in
about 3 hours to produce a positive polarity liquid developing
agent.
Using the liquid developing agent thus prepared, the following
photoreceptor for a printing plate, which had been positively
charged and then imagewise exposed, was processed for reversal
development using a conventional method. A good image was
formed.
PREPARATION OF PRINTING PLATE PRECURSOR
The surface of a JIS 1050 aluminium sheet was sand-finished with a
rotary nylon brush, using a pamis-water suspension as a polishing
agent. The surface roughness (center line mean roughness) of the
finished surface was 0.5 micron. After washing with water, the
sheet was then dipped in an aqueous 10%-sodium hydroxide solution
at 70.degree. C. for etching, whereupon the amount of the dissolved
aluminium was 6 g/m.sup.2. After again washing with water, this
sheet was dipped in an aqueous 30%-nitric acid solution for
neutralization, and then this sheet was further washed with water
sufficiently. Afterwards, the sheet was electrolyzed for
surface-roughening in an aqueous 0.7%-nitric acid solution for 20
seconds, using alternate square waves having an anode voltage of 13
V and a cathode voltage of 6 V (see JP-B-55-19191, for example),
and then this was dipped in a 20% sulfuric acid of 50.degree. C. to
wash the surface thereof. Next, this so treated sheet was washed
with water. Further, this sheet was subjected to anodic oxidation
in an aqueous 20% sulfuric acid solution to form an anodic
oxidation film of 3.0 g/m.sup.2. Last, this sheet was washed with
water and dried, and a printing plate precursor was obtained.
Next, a photoconductive layer-coating composition comprising the
following components was coated on the printing plate precursor
with a bar coater and dried at 120.degree. C. for 10 minutes.
______________________________________ Photoconductive
Layer-Coating Composition: ______________________________________
1. Hydrazone Compound 2.5 parts ##STR15## 2. Copolymer of Benzyl
Methacrylate and 75 parts Methacrylic Acid (methacrylic acid
content: 40 mol %) 3. Thiopyrylium Salt Compound 1.18 parts
##STR16## 4. Methylene Chloride 510 parts 5. Methyl Cellosolve
Acetate 150 parts ______________________________________
The dry film thickness on the printing plate precursor thus
prepared was 4 microns.
EXAMPLE 18
A solution was prepared from the following components.
______________________________________ Graft-Copolymer (3) 10 parts
Nigrosine (Bontron N-01) 1 parts Dichloromethane 100 parts
______________________________________
The solvent was evaporated from the resulting solution to obtain a
color powder. The color powder was added to Isopar G, whereupon
this self-dispersed therein to produce dispersed grains having a
grain size of 0.15 micron. The grains had a positive polarity. 2 g
of the color powder was added to one liter of Isopar G to obtain a
dispersion. A zinc oxide-coated photoreceptor of the ELP Master II
Type (marketed by Fuji Photo Film Co.) was corona-charged to -700 V
in the dark and then imagewise exposed. The thus exposed
photoreceptor was then developed with the dispersion prepared
above, whereupon an image with some image flow was obtained.
EXAMPLE 19
2 g of the color powder as obtained in Example 18 was added to one
liter of Isopar G containing 1.times.10.sup.-6 M zirconium
naphthenate to obtain a self-dispersing dispersion. The dispersed
grains in the dispersion had a grain size of 0.5 micron, the
dispersion had a positive polarity. This was used for development
in the same way as in Example 18 and, as a result, an image with no
image flow was formed with excellent resolving power. The
combination comprising the color powder and the zirconium
naphthenate-containing Isopar G is a toner kit comprising a toner
and a carrier liquid.
As discribed above, in accordance with the present invention a
toner and a colorant which are usable in preparing a liquid
developing agent for electrostatic photography, a printing ink, and
an ink for ink-jet system or a coating paint ink can be produced
without any necessity for mechanical dispersion. Accordingly, a
solid toner supply for a liquid developing agent for
electrophotography as well as a toner kit which does not require
mechanical dispersion before use is provided by the present
invention.
While the invention has been described in detail and with reference
to specific embodiments thereof, it will be apparent to one skilled
in the art that various changes and modifications can be made
therein without departing from the spirit and scope thereof.
* * * * *